The invention relates to a particle detector for positioning in the trajectory or path of the particles in such a way as to ionize the molecules of a gas in the such case of random nuclear particles or to bring about the fission of fissile materials in the case of neutral particles such as neutrons, the ionization or fission being detected by means of two electrodes between which is established a constant electrical field. The invention also relates to a process for the production of such a detector.
In most conventional applications, the ionization chamber defined between the electrodes in a detector of random particles or the fission chamber in a neutron detector are made by simply assembling the electrodes within a body made in several parts so as to permit the installation of the electrodes.
The construction of the particle detector body in a plurality of parts is, however, prejudicial to the satisfactory operation of the detector in certain special applications and particularly when the detector has to be used at high temperatures, for example above 600.degree. C. and when it is arranged in a particularly intense flow of particles. Such a situation more particularly occurs when these detectors are used for measuring the neutron flux in the core of a nuclear reactor. Moreover, in this special case, it is necessary to be able to provide an elongated detector, whose overall dimensions level with its cross-section are as small as possible.
When the particle detector body is made in several parts, it comprises both assembly members and sealing members. Generally, a certain number of these members are made from metal and contain traces of cobalt, tungsten or other metals, whose high temperature activation leads to the complete falsification of the measurements performed by the detector.